Preparation And Surface Modification Of High-Performance Sargassum Horneri Based Activated Carbon

With the depletion of unrenewable resources and concerns about environmental protection, the utilization of macroalgae has received much attention in activated carbon production. Besides, to improve the performance of activated carbon, process reinforcement and optimization have drawn scientists’ eyes, especially surface modification, which can make the activated carbon have selectivity in absorbing contaminants or specific objectives.Activated carbons were prepared from Sargassum Horneri, which is a kind of dominant macroalgaes in Zhejiang Province, by choosing zinc chloride and phosphoric acid activation, respectively, under nitrogen protection. Based on the analysis of chemical compositions and thermogravimetry(TG) of Sargassum Horneri, the optimal process of activated carbon was determined through orthogonal experiments. Furthermore, the so-called Sargassum Horneri based activated carbon prepared at optimal condition was modified by nitric acid, in order to improve the surface functional groups. The activated carbon before and after nitric acid modification were applied in hexavalent chrome adsorption within simulated wastewater.The results indicated that:(1)The performance of Sargassum Horneri based activated carbon could reach the first grade level of wooden granular activated carbon for water purification, which showed Sargassum Horneri’s possible substitute characteristic for traditional territorial activated carbon source.(2) High performance activated carbons could be prepared by zinc chloride activation, with the yield, the specific surface area, the iodine value, and the decolorization rate of caramel, of more than30%,2314.58m2·g-1,835.29mg·g-1,110%, respectively, under an optimal condition of heating rate of10℃·min-1, activation temperature of600℃, activation time of2h, impregnation ratio of4. Sargassum Horneri based activated carbon performed better than that of the macro algae reported.(3)Under the modification of nitric acid, the surface functional groups of Sargassum Horneri based activated carbon was modified by nitric acid increased clearly. Whereas, excessive concentration of nitric acid would demolish the structure of activated carbon, which did negative effect on the absorption performance, which made30%(mass fraction) of nitric acid the optimal condtion. Under such condition, the saturation adsorption capacities of hexavalent chrome was49.1mg·g-1, which increased by30%over activated carbon before modification.(4) The adsorption isotherm of Sargassum Horneri based activated carbon before and after the nitric acid modification adsorption of hexavalent chrome matched Langmuir model, and adsorption rate Lagrange Pseudo-second-order kinetics equation.